CTTNBP2 and infection: Although ORF4 mutations (nonsense mutation or base deletions) were detected in ~20–60% of the virus stock prior to ALI culture, in both SMC-H/1121/04 and SMC-H/1948/04, the full-length ORF4 sequence was almost exclusively detected as early as 4 days post-infection and remained dominant thereafter (Fig. 3a–c and Tables S1–S3).